Abstract:

Systems, devices, and methods for controlling a fuel supply for a turbine
or other engine using direct and/or indirect indications of power output
and optionally one or more secondary control parameters.

Claims:

1. A method of controlling a fuel supply for an aircraft-mounted turbine
engine, the method comprising:monitoring a differential oil pressure
associated with an operating engine, the differential engine oil pressure
determined using signals representing at least two measured operating
engine oil pressures, to determine whether a change in the monitored
differential engine oil pressure has occurred;upon determining that a
change in the monitored differential engine oil pressure has occurred,
using signals representing at least one other aircraft or engine
operating parameter to determine whether the change in differential
engine oil pressure corresponds to a desired change in an output power
level for the engine; andif it is determined that the change in
differential engine oil pressure does not correspond to a desired change
in an output power level for the engine, calculating a desired fuel flow
rate for the engine and providing a corresponding command signal to an
engine fuel supply controller.

2. The method of claim 1, wherein the at least one other operating
parameter comprises an acceleration of at least one portion of an
aircraft.

3. The method of claim 1, wherein the at least one other aircraft of
engine operating parameter comprises at least one of an engine operating
temperature, and engine operating pressure, and air temperature, and an
air pressure.

4. The method of claim 1, wherein the corresponding command signal
provided to an engine fuel supply controller comprises signals adapted to
modify a rate of fuel flow provided to the engine.

5. The method of claim 1, wherein, if a change in differential engine oil
pressure does not correspond to a desired change in an output power level
for the engine a current fuel flow rate to the engine is held for a
determined time interval.

6. A method of controlling a fuel supply for an aircraft-mounted turbine
engine, the method comprising:monitoring a differential oil pressure
associated with an operating engine, the differential engine oil pressure
determined using signals representing at least two measured operating
engine oil pressures, to determine a corresponding indicated engine
output power level;monitoring at least one other aircraft or engine
operating parameter to determine whether the indicated engine output
level corresponds to a desired output power level for the engine; andif
the indicated engine output level does not correspond to the desired
output power level for the engine, calculating a desired fuel flow rate
for the engine and providing a corresponding command signal to an engine
fuel supply controller.

7. The method of claim 6, wherein the at least one other operating
parameter comprises an acceleration of at least one portion of an
aircraft.

8. The method of claim 6, wherein the at least one other aircraft of
engine operating parameter comprises at least one of an engine operating
temperature, and engine operating pressure, and air temperature, and an
air pressure.

9. The method of claim 6, wherein the corresponding command signal
provided to an engine fuel supply controller comprises signals adapted to
modify a rate of fuel flow provided to the engine.

10. The method of claim 6, wherein, if the indicated engine output level
does not correspond to the desired output power level for the engine,
holding a current fuel flow rate to the engine for a determined time
interval.

11. A controller for a fuel supply for an aircraft-mounted turbine engine,
the controller adapted to:receive from at least one transducer input
signals representing a differential engine oil pressure;receive from at
least one other transducer input signals representing at least one other
aircraft or engine operating parameter; andusing the input signals
representing the differential engine oil pressure, determine whether a
change in the differential engine oil pressure has occurred;using input
signals representing the at least one operating parameter, determine
whether the determined change in differential engine oil pressure
corresponds to a desired change in an output power level for the engine;
andupon determining that the determined change in differential engine oil
pressure does not correspond to a desired change in an output power level
for the engine, calculate a desired fuel flow rate for the engine and
provide a corresponding output signal useful for controlling an engine
fuel supply.

12. The controller of claim 11, wherein the at least one other transducer
comprises an accelerometer.

13. The controller of claim 11, wherein the at least one other transducer
comprises at least one of a temperature transducer, and a pressure
transducer.

14. The controller of claim 11, wherein the corresponding output signal is
adapted to modify a rate of fuel flow provided to an engine.

15. A controller for a fuel supply for an aircraft-mounted turbine engine,
the controller adapted to:receive from at least one transducer input
signals representing a differential engine oil pressure;receive from at
least one other transducer input signals representing at least one other
aircraft or engine operating parameter; andusing the input signals
representing the differential engine oil pressure, determine whether a
change in the differential engine oil pressure has occurred;using input
signals representing the at least one operating parameter, determine
whether the determined change in differential engine oil pressure
corresponds to a desired change in an output power level for the engine;
andupon determining that the determined change in differential engine oil
pressure does not correspond to a desired change in an output power level
for the engine, provide an output signal useful for maintaining a current
fuel supply for an engine for a determined time interval.

Description:

TECHNICAL FIELD

[0001]The application relates to the operation of turbine engines and,
more specifically, to methods and apparatus for control of the supply of
fuel provided to gas turbine engines using electronic engine control
systems.

BACKGROUND

[0002]Many new aircraft engines, including both engines currently in
development and engines recently certified for flight use, employ
electronic engine control systems. As well, older aircraft, designed
before electronic control systems were common, are sometimes retrofitted
with such systems. Among other advantages, electronic engine control
systems can help to reduce pilot workload, provide simpler and more
efficient interfaces with modern cockpit control systems, provide
improved protection for engines against extreme operating conditions, and
enhance prognostic and diagnostic capabilities.

[0003]An important parameter to be controlled by an electronic engine
controller in a turboprop or turboshaft engine is engine output power (or
output torque). Such power is most often controlled through control of
the rate of fuel flow provided to the engine.

[0004]For measuring and reporting current engine power output, prior art
engine controllers have typically employed mechanical transducers, such
as phase-shift torque controllers or meters. Such mechanical transducers,
however, require space and add weight to an engine; the addition of
either volume or weight to engines is typically undesirable, particularly
in aerospace applications. In a turboprop or turboshaft engine, for
example, the use of such transducers can require modification of the
reduction gearbox (RGB) and associated components.

SUMMARY

[0005]The disclosure provides, in various aspects, methods, systems, and
devices for controlling the supply of fuel to engines, including
particularly aircraft-mounted turbine engines such as turboshafts or
turboprops.

[0006]In various aspects, for example, the disclosure provides methods of
controlling such fuel supplies, the methods comprising steps of
monitoring a differential oil pressure, such as the differential pressure
measured across the reduction gear box (RGB), associated with an
operating engine, the differential engine oil pressure determined using
signals representing at least two measured operating engine oil
pressures, to determine whether a change in the monitored differential
engine oil pressure has occurred; upon determining that a change in the
monitored differential engine oil pressure has occurred, using signals
representing at least one other aircraft or engine operating parameter to
determine whether the change in differential engine oil pressure
corresponds to a desired change in an output power level for the engine;
and if it is determined that the change in differential engine oil
pressure does not correspond to a desired change in an output power level
for the engine, calculating a desired fuel flow rate for the engine and
either providing a corresponding command signal to an engine fuel supply
controller or causing a current fuel flow rate to be continued for a
determined time interval.

[0007]In further aspects, the disclosure provides methods of controlling
such fuel supplies, in which the methods comprise monitoring a
differential oil pressure associated with an operating engine, the
differential engine oil pressure determined using signals representing at
least two measured operating engine oil pressures, to determine a
corresponding indicated engine output power level; monitoring at least
one other aircraft or engine operating parameter to determine whether the
indicated engine output level corresponds to a desired output power level
for the engine; and if the indicated engine output level does not
correspond to the desired output power level for the engine, calculating
a desired fuel flow rate for the engine and either providing a
corresponding command signal to an engine fuel supply controller or
causing a current fuel flow rate to be continued for a determined time
interval.

[0008]In further aspects the disclosure provides systems and devices,
including controllers, for controlling the supply of fuel to such engines
according, for example, to such methods.

[0009]Further details of these and other aspects of the subject matter of
this application will be apparent from the detailed description and
drawings included below.

DESCRIPTION OF THE DRAWINGS

[0010]Aspects of the disclosure are illustrated in the figures of the
accompanying drawings, which are meant to be exemplary and not limiting,
and in which like references are intended to refer to like or
corresponding parts.

[0011]FIG. 1 is a schematic diagram of a gas turbine engine comprising a
system for controlling a fuel supply for an aircraft-mounted turbine
engine in accordance with the disclosure.

[0012]FIG. 2 is a schematic diagram of a differential oil pressure
transducer suitable for use in implementing embodiments of systems and
methods of controlling a fuel supply for an aircraft-mounted turbine
engine in accordance with the disclosure.

[0013]FIG. 3 is a schematic diagram of an embodiment of a system for
controlling a fuel supply for an aircraft-mounted turbine engine in
accordance with the disclosure.

[0014]FIGS. 4 and 5 are schematic flow diagrams of embodiments of
processes for controlling a fuel supply for an aircraft-mounted turbine
engine in accordance with the disclosure.

[0015]FIG. 6 is a representative plot of oil pressure and vertical
acceleration versus time during a negative-g maneuver by an aircraft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016]Various aspects of embodiments of systems, devices, and methods in
accordance with the disclosure are described through reference to the
drawings.

[0017]FIG. 1 is a schematic diagram of a system 100 for controlling a fuel
supply for an engine 200 in accordance with the disclosure.

[0018]In the example shown, turbine engine 200 is a turboprop engine
suitable for use in providing primary flight power for an aircraft. In
the example, engine 200 comprises a gas generator section 202 and a power
module 212. Gas generator section 202 includes an accessory gearbox (not
shown), a multi-stage compressor 206, a reverse-flow combustor 208, and a
high pressure compressor turbine 210. In the example shown, power module
212 comprises power turbine 214 (which may be multi-stage) and reduction
gearbox (RGB) 216 for stepping down the rotational speed of turbine shaft
220 to a speed appropriate for a driving propeller shaft.

[0019]The operation and interactions of components 202-220 of engine 200
and other engines suitable for use in implementing systems, devices, and
methods according to the disclosure will be well understood by those
skilled in the relevant arts. As will be further understood by those
skilled in such arts, the systems and methods disclosed herein are
suitable for use in controlling fuel supplies for a wide variety of both
turbine and non-turbine engines in addition to those described herein.

[0020]In a gas turbine engine such as a turboprop engine 200 or a
turboshaft engine, engine output power is generally dependent, among
other factors, on the rotational speed of gas generator shaft 220.
Control of the speed of a gas generator such as that of gas generator
section 202, and therefore gas generator shaft 220, of FIG. 1 can be
accomplished by regulating the amount of fuel supplied to the combustion
chamber (e.g., combustor 208 of FIG. 1) in view of other factors such as
altitude, inlet pressure, and inlet temperature.

[0021]In systems and methods according to the disclosure, the amount of
fuel provided to a combustor (or other fuel injection system), and
thereby the engine output power, can be regulated by an electronic engine
control system (EEC 110) such as a Full-Authority Digital Electronic
Control (FADEC) system. Such EECs 110 can use any one or more of a number
of parameters as input in determining the amount of fuel to be supplied
to the combustor in order to achieve or maintain a desired engine power
output. Examples of such parameters can include current output power,
altitude, inlet and outlet air pressures, and inlet and outlet air
temperatures.

[0022]As shaft output power can be expressed as:

Shaft output power=(Shaft torque)×(propeller speed),

primary desirable factors in controlling fuel supply can include propeller
speed (Np) and parameters which are directly proportional to shaft
torque, such as differential engine oil pressure measured across the RGB
in a turboprop and/or stress and/or strain in the shaft. Thus primary
input sources for use by EEC 110 in determining current or desired output
power, and thereby desired fuel flow, can include, for example,
phase-shift torque meters and/or differential oil pressures transducers
placed at, for example, the oil inlet and outlet of the RGB in a
turboprop.

[0023]Thus, as described below, system 100 for controlling the fuel supply
to engine 200, can comprise, among other components, one or more
automatic data processors (e.g. EECs) 110 and one or more sensors or
other input devices 102, 104 for assessing and/or confirming engine
output power levels, for calculating desired fuel flow rates for the
engine 200, and for issuing command signals to fuel pumps and/or other
fuel control components 114 to cause such calculated desired fuel flow
rates to be provided to the engine.

[0024]Primary input sensor(s) 102 may be provided for acquiring signals
representing engine output power or parameters useful in determining
engine output power. Such signals may represent direct measures of output
power (as for example in the case of phase-shift torque controllers,
differential oil pressures, and or propeller speed indicators), or
indirect measures, through measurement of parameters which may be used to
deduce output power.

[0025]Input sensor(s) 104 can be provided to acquire data signals
representing parameters relevant to engine operation or otherwise useful
in confirming the current output power; which, for example may be
indirectly associated with engine performance, and/or used to confirm
conditions in which an engine 200 is operating, and thereby to confirm
the meaning of output readings of one or more transducers 102, and
thereby confirm current and desired engine output and fuel supply
settings. Examples of parameters readable by sensors 104 that can be used
to confirm a primary engine power output indication can include vertical
or other accelerations at the engine location, main oil pressure, which
can for example be affected by aircraft accelerations, and/or the
rotational speed Ng of the gas generator, e.g., section 202 in FIG. 1.
While main oil pressure and accelerometer readings can be used to acquire
information regarding movement of the aircraft or other vehicle in which
an engine is mounted, factors such as Ng can be use to confirm whether in
fact a significant change in engine operation has occurred.

[0026]In the example shown in FIG. 1, system 100 for controlling the fuel
supply of engine 200 comprises an engine output power transducer 102 in
the form of a differential oil pressure transducer 300 such as, for
example, that shown schematically in FIG. 2. As will be understood by
those skilled in the relevant arts, the differential oil pressures
provided by transducer 102, 300 can be interpreted as providing a direct
measure of the output torque of engine 200, and therefore is directly
proportional to engine output power.

[0027]Operation of an embodiment of a fuel control system 100 in
accordance with the disclosure may be described in conjunction with such
a transducer 102, 300. Those skilled in the relevant arts, however, will
understand that phase-shift torque meters and other direct measures of
engine torque can be used as input sources 102.

[0028]In the embodiment shown in FIGS. 1 and 2, differential oil pressure
transducer 102, 300 can be disposed proximate a first stage reduction
gear 224 of RGB 216, and can comprise a ring gear 302, cylinder 304,
piston 306 connected to valve 310, and spring 312. Rotation of ring gear
302 can be resisted by helical splines, which can impart an axial
movement of the ring gear and to piston 306. Movement of piston 306 can
cause valve 310 to move against spring 312, opening a valve orifice and
allowing flow of pressurized oil into torque pressure chamber 314.
Movement of piston 306 can continue until the pressure of oil in chamber
314 is proportional to the torque being transmitted to ring gear 302.
Because external pressure can vary and can affect the total pressure
applied to piston 306, the internal RGB static pressure applied at
chamber 316 can be applied to the reverse side of piston 306, resulting
in measurement of differential oil pressure in the RGB 216. This RGB
differential pressure can be interpreted as a measure of torque applied
to output shaft 219 by the RGB 216, and therefore can be used as a
control parameter in determining and controlling the amount of fuel
supplied to engine 200.

[0029]As will be understood by those skilled in the relevant arts,
transducers 102, including any transducers 300, can be of any suitable
form for accomplishing the purposes described herein; the arrangement
shown in FIG. 2 is merely an exemplary embodiment of a single type of
transducer that can be used in implementing the methods, systems, and
devices disclosed herein.

[0030]FIG. 3 is a schematic diagram of a system 100 for controlling a fuel
supply for an aircraft-mounted turbine engine in accordance with the
disclosure. System 100 is suitable for use, for example, in controlling a
fuel supply for an engine such as that shown at 200 in FIG. 1. System 100
comprises one or more sensors 102 for reading and transducing engine
operating parameters such as, for example, differential oil pressure
(see, for example, sensor 300 of FIGS. 1 and 2), propeller speed Np, and
shaft torque (not shown). System 100 can further comprise one or more
sensors 104 for reading and transducing other parameters associated with
operation of the engine 200, such as, for example, inter-turbine
temperature ITT, engine inlet temperature T1, main oil pressure MOP, and
main oil temperature MOT; and other parameters such as power supply
output 386, relay status 388, A/C discretes 390, cockpit power control
lever (e.g., power control lever rotating variable differential
transformer PCL RVDT 392), and other avionics devices 394. One or more
communications channels 106, 108, such as serial or parallel buses,
electronic engine controls (EECs) 110, 110' and fuel control units (FCUs)
114 are also provided. In the embodiment shown, redundant EECs 110, 110'
are provided.

[0031]As will be understood by those skilled in the relevant arts, the
various components of system 100 may be implemented, separately or
jointly, in any form or forms suitable for use in implementing the
systems, devices, and methods disclosed herein. For example, sensors 102,
104 for reading and transducing engine operating parameters such as
differential oil pressure, shaft stress and/or strain, compressor inlet
pressure, propeller speed Np, inter turbine temperature ITT, compressor
inlet temperature T1 or outlet temperature, main oil pressure MOP, and/or
main oil temperature MOT may be of any mechanical, hydraulic, electrical,
magnetic, analog and/or digital compatible form(s) suitable for use in
implementing desired embodiments of the systems, devices, and methods
disclosed. For example, as suggested by FIG. 2, a pressure transducer
such as differential oil pressure transducer 300 may provide
mechanical/visual output for full or partial manual control of a turbine
engine; in other embodiments, temperature, pressure, or other sensors
providing digital and/or analog electromagnetic and/or mechanical signals
representing the measured parameters may be used. Many suitable types of
transducers are now known; doubtless others will be developed hereafter.

[0032]Selection of suitable sensors, transducers, and/or other devices for
monitoring values of parameters 104 will depend, among other factors such
as cost, weight, etc., on the nature of the parameters to be monitored;
such selection will be well within the scope of those having ordinary
skill in the art, once they have been made familiar with this disclosure.

[0033]Communications channels 106, 108, such as those between sensors 102,
104 and EEC/processor 110 can comprise any single or redundant
communications devices or systems, including for example dedicated,
direct-wire connections, serial or parallel buses, and/or wireless data
communications components, suitable for accomplishing the purposes
described herein. As will be understood by those skilled in the relevant
arts, it can be desirable in some applications, particularly aerospace
applications, to provide sensors 102, 104, communications channels 106,
108, processors 110, and fuel control units (FCUs) 114 in redundant sets,
particularly with respect to devices which generate, transmit, or process
electrical signals. It can further be desirable to provide insulators,
firewalls, and other protective devices between components of systems
100, and particularly redundant components, so as to preclude multiple
failures. Even where a single housing is provided, as in the case for a
housing for a differential oil pressure transducer 300, multiple
redundant sensors may be provided.

[0034]FCU 114 can comprise any relays, switches, and controls, and/or
other components, such as pump and/or valve controls, required to control
fulel supply at the command of EEC(s) 110, as for example by receiving
and appropriately responding to command signals provided by EEC and
configured to provide a desired fuel flow to engine 200. Such components
and the use of them in implementing the systems and methods disclosed
herein will not trouble those of ordinary skill in the art, once they
have been made familiar with this disclosure.

[0035]EECs 110 and FCUs may comprise any single, multiple, combination,
and/or redundant general or special purpose data processors, such as
printed integrated circuit boards and associated or auxiliary components
such as volatile and/or persistent data storage devices 111, relays, and
input/output devices, suitable for accomplishing the purposes described
herein. Such components may comprise any hardware and/or soft- or
firmware and data sets, suitable for use in implementing the systems,
devices, and methods disclosed herein.

[0036]As one example, EEC software contained in the EEC 110 and executed
in processors associated therewith may include filters to condition the
differential oil pressure signal as required. Noise may be present in the
signal due to various phenomena that may appear in the signal at various
frequencies. For example, since the differential pressure oil transducer
300 is located above the RGB 216 in close proximity to the propeller, the
oil pressure transducer 300 may respond to the frequency with which
propeller blades pass the transducer. Pulses within the signal related to
such phenomena could easily be filtered via software to ensure the EEC is
processing a true output power or torque signal.

[0037]A wide variety of suitable transducers, communications units, data
processors, memories, relays, communications devices, fuel control
devices, and other components are now available, and doubtless others
will hereafter be developed. Those skilled in the relevant arts will not
be troubled by the selection of suitable components, once they have been
made familiar with the contents of this disclosure.

[0038]FIGS. 4 and 5 are schematic flow diagrams of exemplary processes
400, 500 for controlling a fuel supply for an aircraft-mounted turbine
engine in accordance with the disclosure. Processes 400, 500 are suitable
for use, in conjunction with systems 100, in implementing controls for
fuel supplies for engines such as that shown at 200 in FIG. 1.

[0039]Process 400 depicts a process for controlling a fuel supply for a
turbine or other engine using direct and/or indirect, or primary,
indications of power output and optionally one or more secondary, or
confirmatory, control parameters according to embodiments of the
disclosure. At 402, a current value or level of power output of the
engine 200 is determined. For example, a direct reading of power output
of shaft 218 can be determined using, for example, a mechanical means
such as a phase shift torque probe. Alternatively, a proportional measure
of power output, such as differential RGB oil pressure, may be employed
as a control parameter, in either case using one or more of sensors 102
to provide signals representing any one or more of such parameters to
EEC(s) 110 (and 110'). For example, as shown at 402 a differential oil
pressure across an RGB may be obtained, using a transducer such as
differential oil pressure transducer 102, 300 of FIG. 2 to provide for
processing by EEC(s) 110 and/or 110', and optionally for long- or short
term storage in one or more memories 111, a signal representative of or
otherwise useful in determining current power output of the engine 200.
FCU 110 may process such signals into any form suitable for further
processing in calculating a desired fuel flow rate and preparing any
desired control command signals.

[0040]At 404 a determination may be made as to whether the power reading
obtained or determined at 402 indicates that a change in power has
occurred. For example, a primary reading of power output of shaft 218
made at 402 can be compared with data representing a previous output
reading previously stored in persistent or volatile digital memory 111 by
EEC 110. From such comparison it can be determined, visually or
automatically, that power output is indicated to have increased or
decreased, or to be desired. A visual determination may be made, for
example, by providing suitable output signals EEC 110 to a cockpit
display for review by a pilot, who can, by repeatedly checking the
display, determine that a change in engine output power is indicated. For
further example, a signal representing a second or subsequent
differential engine oil pressure can be obtained., using a
suitably-configured transducer, such as differential oil pressure
transducer 300 of FIG. 2, data processor 110, and volatile and/or
persistent data storage 111, and compared to one or more
previously-acquired signals, using suitably-programmed mathematical
algorithms, to determine whether a change in the monitored differential
engine oil pressure is indicated to have occurred. Such information may
or may not be communicated to a pilot of the aircraft by EEC 110, 110'.

[0041]If at 404 it is determined that no change in engine power output is
indicated, at 405, the process can return to 402. For example, in an
embodiment using an automatic data processor control in an FCU, process
control can be returned to logic block 402 for one or more subsequent
readings of engine power output indicators, so that continual monitoring
of engine power output can be maintained; at any pass through logical
blocks 402, 404, where a change in engine output power is indicated,
control can proceed to block 406.

[0042]If at 404 it is indicated that a change in engine power output has
occurred relative to one or more previous power readings, or if it
desired to confirm that in fact no change has occurred, at 406 data
representing a secondary, or confirmatory, power and/or fuel control
parameter may be acquired, for use in confirming that a change in power
has actually occurred. Such secondary parameter reading(s) can be used to
affirm or contradict the change in power output indicated at 404.

[0043]For example, it is possible, under some circumstances, particularly
where an indirect measure of power output is used, that an erroneous
change in power output may have been indicated at 404. For example,
during certain maneuvers of an aircraft or other vehicle, such as a
zero-g or a negative-g aircraft operation (which may be encountered for
example during turbulence or in sudden descents), acceleration of oil
within the oil tank may cause an incorrect oil pressure reading, which,
if differential oil pressure is being used as an indicator of engine
power output, can result in an incorrect indication of a power
change--either, for example, by indicating that a change has occurred
when in fact none has, or by exaggerating or minimizing the indication of
a true power change. For example, in such circumstances oil may be
accelerated away from the bottom of the tank where the oil pump is
located, causing the oil pump to cavitate, with a consequent drop in MOP.
Such a drop in MOP can in turn result in a loss of differential oil
pressure which is not necessarily connected with a change in engine power
output. This is illustrated, for example, in FIG. 6, which represents a
plot of oil pressure and vertical acceleration versus time during a
negative-g maneuver by an aircraft or other vehicle.

[0044]FIG. 6 illustrates the effect of vertical accelerations on a number
of parameters that can be used to confirm whether an indicated change in
engine power output has in fact occurred. As may be seen in the Figure,
factors such as main oil pressure (MOP) can be significantly correlated
with vertical acceleration (NZ), and therefore can be useful as in
confirming whether an indicated power change might be erroneous, and in
fact indicate a change in vertical accelerations. Other factors, such as
gas generator speed Ng (NG) and main oil temperature are less strongly
correlated to vertical acceleration, and therefore can be useful in
confirming that in fact no change in output power is likely to have taken
place, despite an indication to the contrary. Those skilled in the
relevant arts will understand that the utility of various operating
parameters in verifying engine performance will depend upon the
construction of a particular vehicle, the operating conditions, and other
factors. The identification and use of many such factors should not
present significant difficulties, once such persons have been made
familiar with this disclosure.

[0045]Thus where at 404 it is indicated that a change in engine power
output has occurred relative to one or more previous power readings, at
406, a secondary power and/or fuel control parameter may be acquired, for
use in confirming that a change in engine output power has actually
occurred, or has occurred at a desired level. This can be useful, for
example, when no change in power setting is desired, as for example where
a FADEC or other system is configured to provide a desired constant power
output: to change power when, for example, in fact no change is desired,
or appropriate, and none has in fact taken place, could cause
inconvenient and even dangerous changes in actual engine power settings.
It can also be useful where, for example, a desired change in engine
power has been requested, but subsequent changes in aircraft operating
conditions cause an apparent change in engine power output that is not
accurate.

[0046]As an example of the use of a secondary or confirmatory parameter to
confirm whether a change in engine power output has occurred, or has
occurred within a desired limit, one or more signals 382 representing
acceleration of one or more parts of the aircraft can be acquired and
interpreted, to determine whether the apparent power change determined at
404, or any part of such apparent power change, is accurate. For example,
signals representing acceleration of the aircraft at, for example, the
location of the engine may be obtained, or determined using acceleration
at one or more other points, transposed mathematically to the location of
the engine to determine whether the engine or any part of it is subject
to acceleration that might cause an erroneous power indication.

[0047]For example, one or more locations on the aircraft or other vehicle
may be equipped with one or more accelerometers 104, 382 (FIGS. 1, 2),
which would provide various components of aircraft vertical, horizontal,
and rotational acceleration to EEC 110 or other flight control computer.
Such parameter(s) (possibly along with other air data parameters such as
air speed and altitude) may in turn be communicated to the engine EEC via
a data bus or other digital or analog communications means 106, 108.
Again, such secondary parameter(s) may be used to determine whether a
change in differential oil pressure detected at 404 is due to aircraft
operations rather than a change in output power.

[0048]In other embodiments, secondary parameter(s) obtained at 406 may
include inputs from other sensors 104, such as gas generator speed or
inter turbine temperature ITT. Engine power output may be calculated
based on these inputs using, for example, a digitized engine performance
module within software stored in or otherwise executed by the EEC 110.
This may then be compared to the power output determined at 402 and/or to
previous power output readings in order to determine whether a change in
power has occurred or is correctly indicated at 402.

[0049]It is also possible to use pilot-initiated control inputs as primary
or secondary indicators of desired power settings. For example, control
input from PCL RVDT 104, 392 can be used to indicate a desired output
setting.

[0050]At 408 it is determined whether or not actual engine power output
needs to be modified to meet current intended flight commands, and if so,
to what extent. For example, data signals representing actual power
output may be compared to data signals representing desired power output,
using known computer algorithms. It having been determined whether the
power setting indicated at 402 is correct or needs correction, control of
the process 400 can be transferred to logic block 412.

[0051]As mentioned above, where it is determined at 408 that actual power
output requires correction, the power output can be modified by
increasing or decreasing the fuel flow f. At 412, the fuel flow f
required to compensate for any difference in indicated and desired or
otherwise commanded power settings is calculated. As will be understood
by those skilled in the relevant arts, calculation of the desired f will
depend upon a number of factors, including the type and model of engine
used, the type and model of aircraft or other vehicle in which it is
installed, the operating conditions of the engine and vehicle, the type
of fuel used and its condition, and optionally others.

[0052]At 414, signals representing the calculated desired or required fuel
flow f is output to the EEC system, for use, for example, in providing
output command signals for a fulel pump or other device, and control of
process 400 can return to 402.

[0053]If it is determined at 408 that a change in power is not desired,
then control of the process 400 passes to logic block 410, at which the
current fuel flow f may be held constant for a fixed or other determined
time interval (for example, ten seconds) and control of the process 400
can returns to control block 402.

[0054]Where an erroneous change in power output had been detected at 404,
the time interval applied at 410 is preferably long enough to allow the
situation which caused the erroneous output power detection to pass, but
in any case is preferably short enough to prevent the development of
other possibly detrimental changes in flight or other vehicle conditions.
For example, in the event that a momentary loss or reduction of MOP is
experienced, as mentioned above and shown in FIG. 5, and a corresponding
loss of differential oil pressure also occurs, at 410 the engine fuel
flow may be held for a predetermined period long enough to give both the
MOP and the differential oil pressure a chance stabilize, so long as no
danger to flight safety has a chance to arise. After the designated time
interval has passed, if the MOP and differential oil pressure have not
recovered (i.e. signaling some other issue such as sensor failure), the
engine power may be reduced, engine control may be governed using another
input/parameter, such as gas generator speed or inter turbine temperature
(ITT) and/or the aircraft may fly in a degraded mode. Alternatively, in
addition to or in lieu of using predetermined intervals of fixed length,
various parameters 102, 104 can be monitored to determine when a
condition giving rise to erroneous power readings has abated, so that
control can be resumed based on primary power indication factors.

[0055]Suitable methods and algorithms for determining fixed or variable
time intervals for application at block 410 in holding current fuel flow
f constant are known, and their use will be within the scope of those
skilled in the relevant arts, once they have been made familiar with this
disclosure.

[0056]FIG. 5 provides a schematic diagram of another embodiment, 500, of a
process for controlling a fuel supply to a turbine or other engine
according to the disclosure, suitable for implementation using systems
and devices disclosed herein, including for example engine 200 of FIG. 1
and system 100 as described. Many of the individual process steps 502,
504, etc., are similar in form and alternative to various steps of
process 400, and form, to some degree, corresponding parts of process
500. Thus in many cases the description below details only those portions
of process 500 which differ significantly from their counterparts in
process 400.

[0057]At 502, a current value or level of power output of the engine 200
is determined. For example, a direct reading of power output of shaft 218
can be determined using, for example, a mechanical means such as a phase
shift torque probe. Alternatively, an indirect or proportional measure of
power output may be employed as a surrogate control parameter using, for
example, one or more of sensors 102 providing signals representing any
one or more of a number of parameters (as, for example, disclosed
herein). For example, as shown at 402 a differential oil pressure across
an RGB may be obtained, using a transducer such as differential oil
pressure transducer 102, 300 of FIG. 2 to provide for processing by
EEC(s) 110, 110' and optionally for long- or short term storage in one or
more memories 111, a signal representative of or otherwise useful in
determining current power output of the engine 200. EEC(s) 110, 110' may
process such signals into any form suitable for further processing in
calculating a desired fuel flow rate and preparing any desired control
command signals.

[0058]At 504 an output signal representing a parameter useful in
confirming the accuracy of the power output indication determined at 502
is obtained. For example, signals representing one or more additional
flight and/or engine operating conditions, including for example
acceleration, altitude, temperature, or other parameters (as for example
described herein), may be obtained, using for example one or more
transducers 104, and provided to EEC(s) 110, 110'.

[0059]At 506, using data acquired at 502, 504, EEC(s) 110,110' can
determine whether the current fuel flow rate f is correct, in view of
current power command settings obtained from, for example, power settings
set by a pilot using a control input such as PCL RVDT 104, 390 or by an
automatic flight control system. For example, as described herein data
representing a differential oil pressure obtained at 502 is used by
EEC(s) 110, 110' executing suitably-configured flight control software,
to determine a corresponding apparent engine power out put; and the
secondary data acquired at 504 is used, as described herein, to confirm
whether the power setting determined using the value acquired at 502 is
correct.

[0060]Once the actual power output determined by comparing the values
acquired at 502, 504 is determined, at 508 EEC 110 can compare the actual
power setting to command power settings indicated by cockpit controls or
other sources, and as described herein a corresponding suitable fuel flow
rate f may be determined and at 510 used to provide corresponding command
signals to a fuel control unit 114 (FIG. 1) or other device.

[0061]If either at 506 the current fuel flow rate f is determined to be
correct or suitable output command signals have been provided at 510,
control can return tic 502 so that continuous or continual monitoring of
engine operating conditions may be maintained.

[0062]The above descriptions are meant to be exemplary only, and those
skilled in the relevant arts will recognize that changes may be made to
the embodiments described without departing from the scope of the subject
matter disclosed. Still other modifications which fall within the scope
of the described subject matter will be apparent to those skilled in the
art, in light of a review of this disclosure, and such modifications are
intended to fall within the appended claims.

[0063]Unless specified herein, or inherently required by the processes
themselves, the order of steps shown in processes disclosed is not
significant, and such order may be changed without departing from the
meaning or scope of the disclosure.